[The syndrome of congenital unilateral hyperfunction of the inferior oblique muscle: clinico-pathogenetic variants]

Area of Science:

• Ophthalmology
• Pediatric Ophthalmology
• Strabismus

Background:

• Early-onset squint can stem from congenital muscular imbalances.
• Unilateral congenital paresis of the superior oblique muscle and unilateral hyperfunction of the inferior oblique muscle are distinct conditions.
• Understanding the underlying mechanisms of these conditions is crucial for diagnosis and treatment.

Purpose of the Study:

• To investigate the relationship between unilateral congenital superior oblique muscle paresis and unilateral hyperfunction of the inferior oblique muscle.
• To identify common clinical features and propose a unifying diagnosis for these conditions.
• To characterize the syndrome of congenital unilateral hyperfunction of the inferior oblique muscle.

Main Methods:

• Clinical examination of 21 children with unilateral congenital superior oblique muscle paresis.
• Clinical examination of 50 children with unilateral hyperfunction of the inferior oblique muscle.
• Analysis of clinical signs including eye deviation in adduction and abduction, and associated strabismus patterns.

Main Results:

• Both conditions exhibit signs of a shared syndrome of oblique muscle dysfunction, indicating a primary congenital defect in muscular balance.
• A consistent sign is unilateral hypertropia in adduction, which diminishes in abduction.
• Associated findings include convergent horizontal squint (frequently esotropia) and a V-sign.

Conclusions:

• The study proposes a unifying syndrome, termed "syndrome of congenital unilateral hyperfunction of inferior oblique muscle", encompassing both conditions.
• This syndrome represents a primary congenital defect in muscular balance affecting oblique eye muscles.
• The identified clinical signs provide a basis for diagnosing this specific type of early squint.